Static versions of the pages are cached, when there are sweeping updates that modify every page (and a change in sidebar counts) then they can take a while to appear everywhere because the software tries to spread out the recomputing of cached pages over time to prevent overloading the server. (Otherwise, something like updating the sidebar on Wikipedia would be basically a denial-of-service attack.)

You can manually force the purge of a given page if you want this page in particular updated right now. I'll leave it as an exercise to the reader to figure out how.